I need some input from the community on an idea that just came to me. I don't know if this is standard practice or not, but it seems to be the most practical solution to the problem.

I am turning some parts in our Haas ST-20 lathe and I am having a couple of problems. First off is that I don't have any jaws bored to the correct diameter for the workpiece. We have a rather small collection of chuck jaws, a problem which I am pushing hard to get resolved, and we need all of the jaws we have, so I can't bore any of them to the diameter of this piece. The part is cut from 1.625 diameter material (6061-T6511B) and is being turned down to 1.588. The part is then flipped and clamped on the 1.588 side. The finished part is 7.875 inches long, which leads to my second problem, which is chatter. I have tried what seems like a hundred combinations of speeds, feeds, and DOC, to no avail. One piece runs perfectly, and the next chatters like an SOB.

My thought is to manufacture a split bushing out of 6061 aluminum with an OD of 2.250, which corresponds to the closest diameter of chuck jaws in our inventory, and an ID of ~1.63 to accommodate the workpiece. I would also make it long enough to support the part farther away from the chuck to help cut down on chatter.

Is this something that is done often? I've done it before to hold an octagonal part in a three jaw chuck, so I know it's doable, but I don't know if it's commonplace or even within the realm of best practices, so I need some input. Feel free to berate me for being a bit of a newbie, as I am already saying it to myself!